(a) Field of the Invention
The present invention relates to a novel oven construction for thermal-magnetic treatment of toroidal coils of amorphous ferro-magnetic ribbon material whereby to improve the eddy current and hysteresis losses thereof for utilizing such coils in a distribution transformer construction.
(b) Description of Prior Art
In my U.S. application Ser. No. 632,065 abandoned in favour of continuation application Ser. No. 003,367, I disclose the construction of a novel distribution transformer wherein the magnetic circuit is formed by one or more toroidal coils made from ribbon of ferro-magnetic amorphous steel material. Such distribution transformers need not be immersed in an insulating oil and thus are not inflammable or vulnerable to fire or explosion in the event of defects or over-heating of the transformer. Furthermore, there is a considerable weight reduction achieved by my novel transformer construction. With prior art distribution transformers, the hysteresis loss as well as eddy current losses are continuous and relatively large. By utilizing my magnetic circuit, and particularly comprising a toroidal coil of amorphous ferro-magnetic ribbon material, I overcome these disadvantages. However, the coil must be treated in order to improve the eddy current and hysteresis losses of the material and this is achieved, in a very efficient manner, by the use of my new oven concept.
It is pointed out that with prior art ovens, it is not possible to produce thermal as well as magnetic fields to treat the coil.